This dent in the Earth's magnetic field, known as the "South Atlantic Anomaly," stretches from South America to southwestern Africa. This mysterious anomaly puzzles scientists. Although this discovery is not new, substantial funding is now being allocated for its research. NASA, with its fleet of satellites and spacecraft, is perhaps the most interested observer.
Overall, the Earth's magnetic field is under threat from a number of alarming factors, including not only the SAA but also the accelerated shift of magnetic poles and the gradual weakening of field intensity. Over the past two centuries, its strength has decreased by 9% (according to ESA's Swarm mission), increasing the risk of cosmic and solar radiation penetration.
It is worth noting that the Earth's magnetic field acts as an invisible shield surrounding our planet, generated by the movement of molten metal in the Earth's outer core. This motion creates electric currents that produce the magnetic field.
Without it, solar wind (a stream of charged particles from the Sun) could strip away our atmosphere, making Earth much less hospitable for life. The magnetic field also aids animals in navigation, enables the operation of many devices, from compasses to spacecraft—and even plays a role in how satellites move in orbit.
Impact of the South Atlantic Anomaly
NASA's interest in the South Atlantic Anomaly is not merely academic curiosity. The anomaly poses a tangible risk, including to their space technologies. When satellites and spacecraft pass through this region in Earth's orbit, they are exposed to the weakened magnetic field within the anomaly.
The reduced field intensity allows charged particles from the Sun to attack the spacecraft, potentially causing malfunctions in onboard technological systems or even short circuits. As a result, satellite operators are compelled to regularly shut down spacecraft systems when approaching the anomaly zone.